The Install Bay PZGBOLT Zinc Anodized Thread Cutting Bolts 5/16 Inch 
Consists of a taper-headed metal cone, Washer, lead sleeve, metal cone and nut completely assembled. When installed, the taper-head metal cone expand the lead sleeve to fill all the pores and crevices of the material in which it is set. Thread cutting and thread rolling screws, two types of self-tapping screws, are threaded fasteners that create a mating thread in the wall of a hole.